Field
The present invention relates generally to calibration of a radio-frequency (RF) transmitter. More specifically, the present invention relates to embodiments for calibrating a power amplifier device with digital pre-distortion.
Background
Electronic amplifiers are used for increasing a power and/or an amplitude of various electronic signals. Most electronic amplifiers operate by using power from a power supply, and controlling an output signal to match the shape of an input signal, while providing a higher amplitude signal.
One widely used type of electronic amplifier is a power amplifier, which is a versatile device used in various applications to meet design requirements for signal conditioning, special transfer functions, analog instrumentation, and analog computation, among others. Power amplifiers are often used in wireless applications, and may employ RF amplifier designs for use in the RF range of the electromagnetic spectrum. An RF power amplifier is a type of electronic amplifier used to convert a low-power RF signal into a signal of significant power, typically for driving an antenna of a transmitter. RF power amplifiers are oftentimes used to increase the range of a wireless communication system by increasing the output power of a transmitter.
Power amplifiers, typically, do not behave in a linear manner. More particularly, power amplifier distortion may compress or may expand an output signal swing of a power amplifier. Signal detectors receiving and decoding the amplified signals typically do not operate in such a non-linear fashion. Therefore, it is usually necessary to linearize an output of a power amplifier. One approach to such linearization is digital pre-distortion (DPD). DPD may be calibrated and used with power amplifiers to invert power amplifier distortion characteristics by expanding compression regions and compressing expansion regions of power amplifier characteristics.
A need exists for calibrating a power amplifier digital pre-distortion device. More specifically, a need exists for embodiments related to calibrating a power amplifier digital pre-distortion device based a non-linearity characterization of the power amplifier digital pre-distortion device.